Re: [Isis-wg] draft-noguchi-isis-protocol-topology-00.txt

Hi Naiming,

This is Kay.

>  ] 	2) Some implementation checks if the IP Interface Address TLV is
>  ] 	   in the same subnetwork or not to form an adjacency as
>  ] 	   stated in draft-ietf-isis-ip-interoperable-00.txt section 13.
>  ] 
>  ] 	   How does M-ISIS software which only supports IPv6 get the IPv4
>  ] 	   subnetwork information for this link?
> 
> as you noticed, this is an implementation issue. and get aournd those
> implementation, one can assign an ipv4 address on the LAN interface,
> and "inject" that ipv4 address in the IIH which is on the same subnet

	So M-ISIS routers which follows draft-ietf-isis-ip-interoperable-00.txt
	section 13 MUST advertise IP Interface Address TLV
	if they want to make adjacent with legacy IPv4 routers on a LAN
	even if M-ISIS routers only support IPv6 IS-IS routing.

	Is this correct?

> as your neighbors. as far as i know, there is no ipv6 only routers yet,
> get an ipv4 address on the LAN interface does not mean the router
> need to switch ipv4 traffic, it can still be a ipv6 only M-ISIS node.

	I don't think this is a good assumption.

	We are talking about "IPv6 only" IS-IS routers so we don't know
	the routers has IPv4 address on the interface or not.

	If they don't have the IPv4 address on the interface, then
	how to encode the IP Interface Address TLV?

> for any new routing scheme, we can not expect a flag day to upgrage
> all the nodes with new software. any scheme HAS to co-exist with the
> current/legacy software. new software has the flexibility to do "tricks"
> to work with the old software.

								kay
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